{"syms", 0x2c2b, 0x55cb},
			{"spsz", 0x0, 0x81f6},
			{"pcsz", 0xf7a, 0x81f6},
		},
	},
	{
		"testdata/amd64-plan9-exec",
		FileHeader{MagicAMD64, 0x618, 0x13, 8, 0x200000, 40},
		[]*SectionHeader{
			{"text", 0x4213, 0x28},
			{"data", 0xa80, 0x423b},
			{"syms", 0x2c8c, 0x4cbb},
			{"spsz", 0x0, 0x7947},
			{"pcsz", 0xca0, 0x7947},
		},
	},
}

func TestOpen(t *testing.T) {

	Data  uint32 /* size of initialized data */
	Bss   uint32 /* size of uninitialized data */
	Syms  uint32 /* size of symbol table */
	Entry uint32 /* entry point */
	Spsz  uint32 /* size of pc/sp offset table */
	Pcsz  uint32 /* size of pc/line number table */
}

// Plan 9 symbol table entries.
type sym struct {
	value uint64
	typ   byte
	name  []byte
}

const (
	Magic64 = 0x8000 // 64-bit expanded header

		f.HdrSize += 8
	}

	var sects = []struct {
		name string
		size uint32
	}{
		{"text", ph.Text},
		{"data", ph.Data},
		{"syms", ph.Syms},
		{"spsz", ph.Spsz},
		{"pcsz", ph.Pcsz},
	}

	f.Sections = make([]*Section, 5)

	off := uint32(f.HdrSize)

	for i, sect := range sects {
		s := new(Section)
		s.SectionHeader = SectionHeader{
			Name:   sect.name,

import (
	"os"
	"runtime"
)

func foo(x int) int {
	return x + 1
}

func test() {
	defer func() {
		if r := recover(); r != nil {
			pcs := make([]uintptr, 10)
			n := runtime.Callers(0, pcs)
			pcs = pcs[:n]
			frames := runtime.CallersFrames(pcs)
			for {
				f, more := frames.Next()
				if f.Function == "main.foo" {
					println("did not expect to see call to foo in stack trace")
					os.Exit(1)
				}

	return sehf4(pan)
}

//go:noinline
func sehf4(pan bool) []uintptr {
	var pcs []uintptr
	if pan {
		panic("sehf4")
	}
	pcs = sehCallers()
	return pcs
}

func testSehCallersEqual(t *testing.T, pcs []uintptr, want []string) {
	t.Helper()
	got := make([]string, 0, len(want))
	for _, pc := range pcs {
		fn := runtime.FuncForPC(pc)
		if fn == nil || len(got) >= len(want) {
			break
		}

// creating it if necessary.
func (c *StackCounter) Inc() {
	pcs := make([]uintptr, c.depth)
	n := runtime.Callers(2, pcs) // caller of Inc
	pcs = pcs[:n]

	c.mu.Lock()
	defer c.mu.Unlock()

	// Existing counter?
	var ctr *Counter
	for _, s := range c.stacks {
		if eq(s.pcs, pcs) {
			if s.counter != nil {
				ctr = s.counter
				break
			}
		}
	}

	if ctr == nil {

var x byte
var p *byte

//go:noinline
func f() {
	q := p
	x = 11  // line 23
	*q = 12 // line 24
}
func main() {
	defer func() {
		recover()
		var pcs [10]uintptr
		n := runtime.Callers(1, pcs[:])
		frames := runtime.CallersFrames(pcs[:n])
		for {
			f, more := frames.Next()
			if f.Function == "main.f" && f.Line != 24 {
				panic(fmt.Errorf("expected line 24, got line %d", f.Line))
			}
			if !more {

// walkFrames calls visit for each call frame represented by pcs.
//
// pcs should be a slice of PCs, as returned by runtime.Callers.
func walkFrames(pcs []uintptr, visit frameVisitor) {
	if len(pcs) == 0 {
		return
	}

	frames := runtime.CallersFrames(pcs)
	for {
		frame, more := frames.Next()
		visit(frame.File, frame.Line, frame.Function, frame.PC-frame.Entry)

package runtime_test

import (
	"fmt"
	"runtime"
	"strings"
)

func ExampleFrames() {
	c := func() {
		// Ask runtime.Callers for up to 10 PCs, including runtime.Callers itself.
		pc := make([]uintptr, 10)
		n := runtime.Callers(0, pc)
		if n == 0 {
			// No PCs available. This can happen if the first argument to
			// runtime.Callers is large.
			//
			// Return now to avoid processing the zero Frame that would

//go:noinline
func child7bad() {
}

//go:noinline
func child7() {
	// Write runtime.Caller's view of the stack to stderr, for debugging.
	var pcs [16]uintptr
	n := runtime.Callers(1, pcs[:])
	fmt.Fprintf(os.Stderr, "Callers: %#x\n", pcs[:n])
	io.WriteString(os.Stderr, formatStack(pcs[:n]))

	// Cause the crash report to be written to stdout.
	panic("oops")
}

// TestTracebackSystem tests that the syntax of crash reports produced